Row 3 and 4 are the memory demultiplexer and the memory itself.
To save wires and relays, I use resistors to latch the relays. The advantage of it is that clocking +24V will latch a bit ON and clocking the GROUND will latch it OFF.
A relay can still hold the on-position with less than half of the nominal coil voltage, so this hack is very useful.

I´ll modify my actual design to this kind of latching also for the address- and ALU-multiplexers. It will make the computer more powerful with a minimal amount of effort.